Adenovirus infections are widespread in society and are occasionally associated with severe, but rarely with life-threatening, disease in otherwise healthy individuals. In contrast, adenovirus infections present a real threat to immunocompromised individuals and can result in disseminated and fatal disease. The number of patients undergoing immunosuppressive therapy for solid organ or hematopoietic stem cell transplantation is steadily increasing, as is the number of AIDS patients, and this makes the problem of adenovirus infections even more urgent to solve. There is no formally approved treatment of adenovirus infections today, and existing antiviral agents evaluated for their anti-adenoviral effect give inconsistent results.
Human adenoviruses are very common pathogens and comprise at least 51 different serotypes; together, these form six different species, A-F. Adenoviruses (Ads) are associated with a wide variety of clinical symptoms in humans, such as upper respiratory illness, acute respiratory disease, gastroenteritis, hemorrhagic cystitis, and even keratoconjunctivitis (Wadell, G. 1984. Molecular epidemiology of human adenoviruses. Current topics in microbiology and immunology 110:191-220. Wadell et al. 1999. Adenoviruses, p. 970-982. In. Murray et al. (eds.), Manual of Clinical Microbiology, 7th ed. ASM Press.).
These infections can result in severe disease, although an Ad infection is most commonly self-limited in otherwise healthy individuals. The problem is much more pronounced in immunocompromised individuals. This group is steadily growing as a result of increasing numbers of AIDS patients and patients undergoing immunosuppressive therapy for solid organ or hematopoietic stem cell transplantation, and also because of increased survival times of these patients. Immunocompromised individuals are at high risk of developing disseminated disease and multiple organ failure, and an Ad infection can become a serious life-threatening disease (Janney et al. 1990. Fatal adenovirus infection in a child with acquired immunodeficiency syndrome. Pediatr. Infect. Dis. J. 9:434-436). In immunocompromised children, Ads are an important cause of disease and case fatality rates of above 50% have been reported (Hierholzer 1992. Adenoviruses in the immunocompromised host. Clinical Microbiology Reviews 5:262-274). In pediatric bone marrow transplant (BMT) recipients the incidence of Ad infection is substantially higher than in adult BMT recipients (Baldwin et al. 2000. Outcome and clinical course of 100 patients with adenovirus infection following bone marrow transplantation. Bone Marrow Transplantation 26:1333-1338).
A number of different Ads have been isolated from immunocompromised patients, most frequently from species A, B, or C (Kojaoghlanian et al. 2003. The impact of adenovirus infection on the immunocompromised host. Rev Med Virol 13:155-71). Species B serotypes are predominantly associated with renal syndromes and species C serotypes are usually associated with hepatitis. In recent years, infections with Ad serotype 31 (species A) have been increasingly reported and they often occur in patients with infections involving multiple Ad serotypes, occasionally with lethal outcome (Leruez-Ville et al. 2006. Description of an adenovirus A31 outbreak in a paediatric haematology unit. Bone Marrow Transplant 38:23-28.).
There are no approved specific antiviral compounds for treatment of Ad infections available today. Established antiviral drugs including cidofovir, ribavirin, and ganciclovir have been tested for anti-adenoviral activity both in in vitro experiments and in the clinical setting. The clinical efficacy is inconclusive, since varying results have been reported for the drugs. Of the approved drugs, Cidofovir appears to be most effective against Ads (Morfin et al. 2005. In vitro susceptibility of adenovirus to antiviral drugs is species-dependent. Antiviral Therapy 10:225-229). However, cidofovir is associated with nephrotoxicity and acute renal failure (Izzedine et al. 2005. Antiviral Drug-Induced Nephrotoxicity. American Journal of Kidney Diseases 45:804-817). The need for new anti-adenoviral substances is clearly increasing due to the large number of immuno-compromised patients undergoing transplantations, and also patients suffering from AIDS or with genetic immunodeficiencies.
Herpes viruses are divided into alpha, beta and gamma herpes viruses. All studied herpes viruses enter a latent state after the primary infection. This means that they later in life can be activated and cause morbidity and in immunocompromized persons even mortality. Herpes simplex virus (HSV)1 & 2 and varicellae virus are the members of alpha herpes viruses. The U-L 23 gene of HSV encodes a nucleoside kinase also called thymidine kinase. This gene product is targeted by acyclovir and its derivatives. This is an effective therapeutic drug against HSV 1 & 2 and it has also been used against varicella-zoster (VZ) infections in adults and immunocompromized children and adults. There is however a need for new alternative antiviral drugs that can be used on acyclovir resistant strains and viruses that do not express a thymidine kinase.
Screening of large compound collections with purified protein or whole cell-based assays, i.e. high-throughput screening (HTS), is a common method to identify biologically active compounds. Cell-based approaches are commonly more labor-intensive but have the benefit of a wider screening without the limitation of having a preconceived idea of the mechanism of action. We have developed a unique whole-cell reporter gene assay based on a GFP-expressing replication-competent Ad vector (Sandberg et al. 2009. Replication-Competent Ad11p Vector (RCAd11p) Efficiently Transduces and Replicates in Hormone-Refractory Metastatic Prostate Cancer Cells. Human Gene Therapy 20:361-373). The assay can identify compounds that directly or indirectly affect adenoviral protein expression. This assay was used to screen approximately 9,800 compounds, resulting in a number of compounds that have an inhibitory effect on Ads without killing the host cells. The inhibitory effect was ascertained at four different stages of the viral replication cycle. Here, we describe the screening method and report on a novel inhibitors of Ad replication that is effective on Ad types representing the six species of human adenoviruses as well as on Herpes simplex virus 1 (HSV-1).
US 2006/0035245 describes a method for identifying anti-HIV agents comprising
i) determining the effect of the agent on the activity of Tn5 transponase, and
ii) determining if the agent can inhibit HIV integrase. The compound 2-[[2-(Benzoylamino)benzoyl]amino]-benzoic acid (herein referred to as compound A02) was found to inhibit Tn5 transponase, but failed to inhibit HIV integrase.